1. Field of the Invention
The present invention relates to a liquid crystal display screen with a carbon-nanotube based alignment layer.
2. Discussion of Related Art
Referring to FIG. 6, a conventional liquid crystal display screen 100 for a liquid crystal display (LCD), according to the prior art, generally includes a first substrate 104, a second substrate 112, and a liquid crystal layer 118. The first substrate 104 is disposed parallel to the second substrate 112. The liquid crystal layer 118 is located between the first substrate 104 and the second substrate 112. A first transparent electrode layer 106 and a first alignment layer 108 are formed in that order on an inner surface of the first substrate 104 that faces toward the liquid crystal layer 118. A first polarizer 102 is formed on an outer surface of the first substrate 104 that faces away from the liquid crystal layer 118. A second transparent electrode layer 114 and a second alignment layer 116 are formed in that order on an inner surface of the second substrate 112 that faces toward the liquid crystal layer 118. A second polarizer 110 is formed on an outer surface of the second substrate 112 that faces away from the liquid crystal layer 118.
The quality and performance of the alignment layers 108, 116 are key factors that determine the display quality of the liquid crystal display screen 100. A high quality liquid crystal display screen demands steady and uniform arrangement of liquid crystal molecules 1182 of the liquid crystal layer 118. This is achieved in part by correct arrangement of the liquid crystal molecules 1182 at the alignment layers 108, 116. Materials to make the alignment layers 108, 116 are typically selected from the group consisting of polystyrene, polystyrene derivative, polyimide, polyvinyl alcohol, epoxy resin, polyamine resin, and polysiloxane. The selected material used to create a preform of each alignment layer 108, 116. The preform is then treated by one method selected from the group consisting of rubbing, incline silicon oxide evaporation, and atomic beam alignment micro-treatment. Thereby, grooves 1082 or 1162 are formed on the treated surface of the preform, and the alignment layer 108, 116 is obtained. The grooves 1082 or 1162 affect the arrangement and orientations of the liquid crystal molecules 1182.
In the liquid crystal display screen 100, the liquid crystal molecules 1182 are cigar-shaped. A plurality of the parallel first grooves 1082 is formed at an inner surface of the first alignment layer 108. A plurality of the parallel second grooves 1162 is formed at an inner surface of the second alignment layer 116. A direction of alignment of each of the first grooves 1082 is perpendicular to a direction of alignment of each of the second grooves 1162. The grooves 1082, 1162 function so as to align the orientation of the liquid crystal molecules 1182. In particular, the liquid crystal molecules 1182 adjacent to the alignment layers 108, 116 are aligned parallel to the grooves 1082, 1162 respectively. When the grooves 1082 and 1162 are at right angles and the substrates 104, 112 are spaced an appropriate distance from each other, the liquid crystal molecules 1182 can automatically twist progressively over a range of 90 degrees from the top of the liquid crystal layer 118 to the bottom of the liquid crystal layer 118.
The polarizers 102 and 110 and the transparent electrode layers 106, 114 play important roles in the liquid crystal display screen 100. However, the polarizers 102, 110 and the transparent electrode layers 106, 114 may make the liquid crystal display screen 100 unduly thick, and may reduce the transparency of the liquid crystal display screen 100. Moreover, the polarizers 102, 110 and the transparent electrode layers 106, 114 typically increase the cost of manufacturing the liquid crystal display screen 100.
What is needed, therefore, is to provide a liquid crystal display screen with a simple structure, reduced thickness, and good arrangement of liquid crystal molecules.